Question

How do you simplify the expression `costheta(sectheta-costheta)`?

Answer 1

We know that `secbeta = 1/cosbeta`.

`=>cos(1/costheta - costheta)`

`=>1 - cos^2theta`

Since `sin^2beta + cos^2beta = 1`:

`=> sin^2theta`

Hopefully this helps!